Independent analysis puts a SGN survodutide lot at 96.5%, against 95.8% on the certificate

VendorInvestigate has released a batch of 18 analytical reports on research-grade survodutide lots, including material from SGN and SSA. Reported purities range across roughly 0.9 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 30 mg vial corresponds to roughly 6.44 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.

The Journal purchased 13 vials from the same lot at retail and had four of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is quoted as a priced addition by most of the twenty companies in the Journal’s dossier programme rather than carried as a standard release test. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.

Dr Wenjun Xie, process chemist and peptide manufacturing consultant, wanted the wavelength printed. "A method reading at 280 nanometres cannot see a fragment that has lost its aromatic residue. That is not a failure of the laboratory, it is a fact about the question they were asked."

SGN’s dossier has been updated with this determination and with the company’s response to it. The dossier’s ordering box records the lead times, the minimum quantities and what a buyer should ask for at the point of order.